An increasing number of recent signboard ads are featuring logos and patterns of vivid colors and sophisticated designs or are photographic in nature capturing the appearances of products, faces of people, etc. In terms of signboard sizes, a considerable number of signboards are now large in size, so they have stronger impact on the people who see them.
Traditional methods for producing signboard ads generally involve cutting colored sheets into the shapes of letters and then attaching the letters to create logos, or using various printing machines to create photographic ads. This presents such problems as requiring a lot of time and labor, and large equipment such as printing machines, to produce signboard ads.
Accordingly, attempts are made to make it easier to produce signboards featuring vivid images using the inkjet method that allows a design created on a personal computer to be printed directly onto a base material.
The inkjet method is characterized in that it supports a wide range of materials for use as printing base materials, making printing onto paper sheets, polymer sheets, metal sheets, and sheets made of other hard or soft materials, easy and convenient. Signboard ads and the like that are installed outdoors must meet such performance requirements as being lightweight, excellent in strength and durability, resistant to rain, and inexpensive, which makes the ability to easily print on polymer sheets having these characteristics a great advantage.
In addition, super-wide-format inkjet printers having a printing width of 2,000 mm or greater have also emerged of late, making signboard production much easier by allowing a large sheet to be printed at once, instead of having to attach smaller sheets together as has traditionally been done.
In general, polymer sheets called “tarpaulins” are often used for signboard ads. A tarpaulin is a composite sheet comprising a polyester or polyamide as core material, and polyvinyl chloride, ethylene-vinyl acetate copolymer, or other vinyl polymer layers stacked on top and bottom of the core material.
Among the inkjet ink compositions with which to print these composite sheets, non-aqueous inkjet ink compositions based on organic solvents (or environmentally-friendly organic solvents lately) are used.
Wide-format inkjet printers carrying ink compositions of orange, green, and other special colors to further expand the color ranges are available on the market lately (refer to Patent Literature 1, for example). However, many of traditional orange ink compositions are relatively low in weather resistance, which gives rise to a need for orange ink compositions offering high weather resistance.